Assessment of Pollution Load Indices of Heavy Metals in Cassava Mill Effluents Contaminated Soil: a Case Study of Small-scale Processors in a Rural Community in the Niger Delta, Nigeria
Sylvester Chibueze Izah
Sunday Etim Bassey
Elijah Ige Ohimain
Department of Biological Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria
Bioscience Methods, 2017, Vol. 8, No. 1
Received: 15 Sep., 2017 Accepted: 30 Oct., 2017 Published: 17 Nov., 2017
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Cassava mill effluents are discharged into the environment by smallholder cassava processor in rural communities in the Niger Delta region of Nigeria. Cassava mill effluents are known to induce toxicity in some biodiversity such as livestock (sheep, goat), vegetation, microorganisms and fisheries. This study evaluated the pollution load indices of heavy metals in cassava mill effluents contaminated soil in rural community in the Niger Delta region of Nigeria. Secondary data from cassava mill effluents soil were used for the study. The data were classified based on seasons. The pollution load was calculated following standard protocol. Nine pollution indices were considered including Contamination factor (CF), Degree of contamination (CD), Pollution load index (PLI), Pollution index (PI), Sum of pollution index (SPI), Pollution index/ Contamination Index (PI/CI), Metal pollution Index (MPI), Average Pollution Index (API) and Nemerow integrated pollution index (NIPI). In few instance that some heavy metals was not detected, 50% of mean detected individual metals were considered for the location that the metals were not detected. Geometric (BGM) and median mean (BMM) were considered for the background scenarios except for API and PI/CI in which median mean was used. The pollution load resulting from these heavy metals viz: Fe, Cr, Zn, Cu, Co, Ni, Mn, Pb and Cd revealed that CF and CD had low to moderate contamination level in both seasons apart from Pb that had considerable pollution in one of the locations for wet season, PLI were within no pollution to moderate pollution, PI were also within no pollution to low pollution level and NIPI were within warning line of pollution to low level of pollution for dry season, and warning line of pollution to high pollution in wet season. MPI, PI/CI and API showed slight pollution. The findings of this study also showed that cassava processing by smallholder in rural communities in the Niger Delta is slightly contributing to heavy metals pollution is receiving soil which varies according to seasons. Furthermore, age and heavy metal content in the cassava tuber and quantity of cassava processed in each mill and other anthropogenic activities could account for difference in pollution among the various locations, while runoff resulting from rainfall could account for the seasonal influence.
Cassava mill effluents; Degree of contamination; Heavy metals; Pollution load